A child and sled with a combined mass of 45. 0 kg slide down a frictionless slope. If the sled starts from rest and has a speed of 2. 20 m/s at the bottom, what is the height of the hill?.

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.